Coach (1978)

An adult female high school basketball coach has a sexual affair with one of the high school boys she is coaching (not disclosed if he is 18 or under). They have sex at her house, although only them in bed afterwards is shown, with no nudity. She also has an erotic encounter with him in the high school gym shower, again nothing shown but his partial nude butt. Four high school girls simultaneously flash their breasts at their boyfriends. A woman in a wet white t-shirt, nipples vaguely visible through it. A group of nude high school boys in the gym shower, one nude butt and maybe an extremely brief glimpse of a penis (was in the background, side view of one of them...may have just been a shadow or something, but I thought it was his penis). A high school boy jokingly tells the female coach that he is so well endowed that it's hard to find a jockstrap that will fit. A high school boy from an opposing school gropes the female coach.

Rival high school basketball teams have a fight after one player attacks in defense of his female coach who has just been groped.